Previous work has shown length of time in drug abuse treatment is associated with better outcomes, but the role of therapeutic engagement and process needs further examination. In this study, the total number of counseling sessions attended by 557 clients in their first 90 days of community-based outpatient treatment was examined in relation to indicators of treatment delivery and progress. Significant client improvements were found on behavioral criteria and psychosocial functioning during the first 3 months of treatment, and session attendance was positively related to favorable behavioral changes as well as to positive perceptions by clients and counselors of their therapeutic interactions. Client background, treatment motivation, and therapeutic focus of counseling in Month 1 were significant predictors of session attendance in the first 3 months following admission to methadone treatment.